I agree about the tech savvy point. There may be a correlation between age or tech savviness and those who know about Craig’s List…similar to sites like MySpace or YouTube. Older or less-savvy folks may certainly use the Internet and know about the bigger sites like Realtor.com, but I think Craig’s List may be a bit more secluded. Another obvious point would be to look at total population and home unit figures. I would guess that San Diego simply has more people and housing units available for listing.